i recall that in 1957 when e m s namboodripad became the chief minister of kerala, one english newspaper carried the news with the headlines "opposition forms government in kerala".
it was because it was considered to be the divine right of congress to form governments and for all other parties to be 'opposition'. this mentality persists in congress. that explains why sharad pawar who was number three in the cabinet (after pranab mookerjee) did not become number two after the exit of mookerjee. how could a non congress minister become number two? so antony had to be appointed.
that is also the reason why man mohan singh repeatedly talks of difficulties of coalition government. congress wants to take a decision and expects all others to endorse it. it is called 'concensus' as per congress. prior consultations are a taboo.